comments@captioncolorado.com >> couric: tonight, emergency workers return to japan's crippled nuclear plant after soaring radiation forces a retreat. and the u.s. tells americans to evacuate a 50-mile danger zone. i'm katie couric. also tonight, the question everyone in this country is asking: could it happen here? the u.s. has 23 nuclear reactors just like those in japan. how safe are they and we? and as the search goes on for victims of the earthquake and tsunami, an american exchange teacher is among the missing. captioning sponsored by cbs from cbs news world headquarters in new york, this is the "cbs evening news" with katie couric. >> couric: good evening, everyone. they have what could be the most dangerous job in the world, and the world is rooting for them to get it done. the nuclear power plant workers in japan trying to prevent a meltdown. radiation at the dai-ichi plant in fukushima got so high today they were forced to leave temporarily, but now they're back on the job. japan has raised the maximum radiation dose allowed for nuclear workers so they can deal with the crisis, but

on the job. japan has raised the maximum radiation dose allowed for nuclear workers so they can deal with the crisis, but the head of the u.s. nuclear regulatory commission told congress today the doses those workers could be exposed to are potentially lethal in a short period of time. it's nearly six days now since the earthquake and tsunami killed at least 4300 people and damaged the nuclear reactors. today, u.s. officials told americans within 50 miles of the plant to evacuate the area or stay indoors. that is two and a half times as wide as the danger zone established by the japanese. harry smith begins tonight's coverage of the disaster in japan. >> reporter: in a sign of how grave japan's crisis has become, the emperor, akihito, made an unprecedented television address, acknowledging that he is deeply worried, urging his subjects not to give up. it did little to calm a country increasingly distrustful, given the wave of conflicting reports and mixed messages. >> ( translated ): there is both positive and negative news. i don't know which i should believe. >> reporter: and toda

Excerpts 0 to 1 of about 2 results.